JP2011196607A - Cooling system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cooling system capable of properly controlling a refrigeration capacity of load-side cooling equipment while suppressing fluctuation of saturated pressure of a COreceiver regardless of heat quantity of the load-side cooling equipment and a cooling capacity of a CO/NHnatural refrigerant cooling system.SOLUTION: In this cooling system 1, a saturated pressure of COliquid refrigerant in the COreceiver 4 is detected by a COpressure sensor 11, and an NHcompressor 7 of an NHrefrigerant circuit is linearly controlled by an inverter 13 to make the saturated pressure of the COliquid refrigerant constant. Thus, the saturated pressure of the COliquid refrigerant in the COreceiver 4 can be controlled constant to the fluctuation of the heat quantity of the load-side cooling equipment 3, and the COliquid refrigerant can be stably fed from a COliquid pump 6. That is, by controlling the saturated pressure in the COreceiver 4 to be constant to the fluctuation of the heat quantity of the load-side cooling equipment 3, the liquid can be stably fed from the COliquid pump 6.

Description

The present invention relates to a cooling system applied to a refrigeration apparatus, an air conditioner, and the like, and more particularly to a cooling system that controls the saturation pressure of a carbon dioxide (CO ₂ ) receiver used in the refrigeration apparatus, the air conditioner, and the like. is there.

In recent years, from the viewpoint of global environmental conservation such as prevention of ozone layer destruction and prevention of global warming, as a refrigerant for refrigeration equipment and air conditioning equipment, instead of Freon, it is a natural refrigerant with an ozone destruction coefficient of zero, and Ammonia (NH ₃ ), whose global warming potential is almost zero, has come to be used. However, since NH ₃ is toxic to the human body, it does not supply the cold heat of the ammonia refrigerant circuit directly to the load side, but is a refrigerant similar to NH ₃ , but uses non-toxic carbon dioxide (CO ₂ ) as the refrigerant. A CO ₂ / NH ₃ natural refrigerant cooling system having a structure for supplying cold heat to a load side through a secondary refrigerant circuit which is a carbon dioxide (CO ₂ ) refrigerant circuit to be used has been put into practical use (for example, patents) Reference 1).

In such CO ₂ / NH ₃ natural refrigerant cooling system, CO ₂ refrigerant circuit for a CO ₂ refrigerant utilizes cold produced by the NH ₃ refrigerant circuit for the NH ₃ and the refrigerant as a condenser cold, the CO ₂ The liquefied CO ₂ liquid refrigerant is stored in the CO ₂ receiver. Then, the CO ₂ liquid refrigerant is sent to a load side cooling facility such as a refrigeration apparatus or an air conditioner by a CO ₂ liquid pump. Furthermore, among the CO ₂ liquid refrigerant whose heat has been exchanged with the load-side cooling equipment, vaporized CO ₂ liquid refrigerant, is condensed through the CO ₂ / NH ₃ cascade condenser back to CO ₂ receiver, not vaporized CO ₂ The liquid refrigerant is configured to return directly to the CO ₂ receiver.

At this time, the saturation pressure of the CO ₂ receiver is controlled by setting the saturation pressure of the CO ₂ receiver for the pressure increased by the heat amount of the load-side cooling facility and the outside air entrance heat amount to the set value or less by operating the NH ₃ refrigeration cycle. The pressure is lowered. Note that the cooling capacity of the NH 3 refrigeration cycle is controlled by detecting the low-pressure side pressure of the NH ₃ refrigeration cycle and controlling the capacity of the NH 3 compressor by stepwise control (that is, step control).

JP 2002-243350 A

However, when the required heat quantity of the load-side cooling equipment is small, or when the heat quantity of the load-side cooling equipment decreases sharply by controlling multiple coolers individually, the NH3 compressor step-by-step capacity control follows. It may not be possible. In such a case, the cooling capacity on the NH3 refrigeration cycle side increases with respect to the heat amount of the load side cooling facility, and as a result, the saturation pressure of the CO2 receiver rapidly decreases. When the saturation pressure of the thus CO ₂ receiver is rapidly reduced, boiling with CO ₂ liquid refrigerant in the CO ₂ receiver (boiling) occurs. As a result, a cavitation phenomenon occurs on the suction side of the CO ₂ liquid pump for supplying the CO ₂ liquid refrigerant to the load side cooling facility. For this reason, there is a possibility that the liquid delivery of the CO ₂ liquid refrigerant from the CO ₂ / NH ₃ natural refrigerant cooling system side to the load side cooling facility may become unstable, causing a cooling failure or the like in the load side cooling facility.

Therefore, regardless of the amount of heat in the load-side cooling equipment and the cooling capacity of the CO ₂ / NH ₃ natural refrigerant cooling system, the fluctuation of the saturation pressure of the CO ₂ receiver is suppressed and the refrigeration capacity of the load-side cooling equipment is appropriately adjusted. The technical problem which should be solved in order to implement | achieve the cooling system which can be controlled arises, and this invention aims at solving this problem.

  The present invention has been proposed to achieve the above object, and the invention according to claim 1 is applied to a primary refrigerant / secondary refrigerant / cooling system, and a secondary refrigerant heat-exchanged by the primary refrigerant is used. A cooling system that cools a load-side cooler by detecting a saturation pressure in a secondary refrigerant receiver that stores the liquid refrigerant of the secondary refrigerant, and compressing the primary refrigerant according to the saturation pressure The cooling system is characterized in that the saturation pressure in the secondary refrigerant receiver is controlled to be constant by linearly controlling the cooling capacity of the primary refrigerant compressor.

  According to this configuration, the saturation pressure in the secondary refrigerant receiver that stores the liquid refrigerant of the secondary refrigerant is detected in the cooling system that cools the load-side cooler using the secondary refrigerant heat-exchanged by the primary refrigerant. Then, the saturation pressure in the secondary refrigerant receiver is controlled to be constant by linearly controlling the cooling capacity of the primary refrigerant compressor that compresses the primary refrigerant in accordance with the detected saturation pressure. As a result, the saturation pressure in the secondary refrigerant receiver is appropriately controlled in accordance with the cooling capacity of the primary refrigerant compressor, so that a sudden drop in the saturation pressure in the secondary refrigerant receiver due to the load fluctuation of the cooler is avoided. be able to.

  In the invention according to claim 2, the saturation pressure in the secondary refrigerant receiver is controlled by an inverter that detects the saturation pressure in the secondary refrigerant receiver and performs frequency control to drive and control the primary refrigerant compressor. The cooling system according to claim 1, wherein the cooling system is controlled to a constant pressure.

  According to this configuration, the saturation pressure in the secondary refrigerant receiver is maintained at a constant pressure by driving the primary refrigerant compressor while the inverter performs frequency control based on the detection information of the saturation pressure in the secondary refrigerant receiver. Controlled. In this way, the saturation pressure in the secondary refrigerant receiver can be controlled to be constant only by driving and controlling the primary refrigerant compressor by varying the frequency of the inverter in accordance with the saturation pressure in the secondary refrigerant receiver. Therefore, it is possible to control the pressure in the secondary refrigerant receiver with a very simple control system.

  According to a third aspect of the present invention, the saturation pressure in the secondary refrigerant receiver is a constant pressure by detecting the saturation pressure in the secondary refrigerant receiver and controlling the number of the two or more primary refrigerant compressors. The cooling system according to claim 1 is controlled.

  According to this configuration, the saturation pressure in the secondary refrigerant receiver is controlled to a constant pressure by controlling the number of primary refrigerant compressors based on the detection information of the saturation pressure in the secondary refrigerant receiver. In this way, the number of primary refrigerant compressors is controlled according to the saturation pressure in the secondary refrigerant receiver, and each compressor is controlled linearly, so the pressure in the secondary refrigerant receiver can be controlled with a more precise control system. Control can be performed.

  The invention according to claim 4 is a cooling system in which the ammonia used in the carbon dioxide / ammonia natural refrigerant cooling system is used as a primary refrigerant and the carbon dioxide is used as a secondary refrigerant. The saturation pressure in the carbon dioxide receiver is detected by detecting the saturation pressure in the stored carbon dioxide receiver and linearly controlling the cooling capacity of the ammonia compressor that compresses the ammonia based on the detected saturation pressure. Provided is a cooling system characterized by constant control.

  According to this configuration, in the cooling system that cools the load-side cooler using the carbon dioxide refrigerant heat-exchanged by the ammonia refrigerant, the saturation pressure in the carbon dioxide receiver that stores the liquid refrigerant of carbon dioxide is detected, According to the detected saturation pressure, the saturation pressure in the carbon dioxide receiver is controlled to be constant by linearly controlling the cooling capacity of the ammonia compressor that compresses the ammonia refrigerant. Thereby, since the saturation pressure in the carbon dioxide receiver is appropriately controlled according to the cooling capacity of the ammonia compressor, it is possible to avoid a sudden decrease in the saturation pressure in the carbon dioxide receiver due to the load fluctuation of the cooler. .

  According to a fifth aspect of the present invention, the saturation pressure in the carbon dioxide receiver is made constant by an inverter that detects the saturation pressure in the carbon dioxide receiver and performs frequency control to drive and control the ammonia compressor. 5. The cooling system according to claim 4, wherein the cooling system is controlled.

  According to this configuration, the saturation pressure in the carbon dioxide receiver is controlled to a constant pressure by driving and controlling the ammonia compressor while the inverter performs frequency control based on the detection information of the saturation pressure in the carbon dioxide receiver. The In this way, the saturation pressure in the carbon dioxide receiver can be controlled to be constant by simply varying the frequency of the inverter in accordance with the saturation pressure in the carbon dioxide receiver and driving and controlling the ammonia compressor. It becomes possible to control the pressure in the carbon dioxide receiver with a simple control system.

  In the invention according to claim 6, the saturation pressure in the carbon dioxide receiver is controlled to a constant pressure by detecting the saturation pressure in the carbon dioxide receiver and controlling the number of the two or more ammonia compressors. The cooling system according to claims 4 and 5 is provided.

  According to this configuration, the saturation pressure in the carbon dioxide receiver is controlled to a constant pressure by controlling the number of ammonia compressors based on the detection information of the saturation pressure in the carbon dioxide receiver. In this way, the number of ammonia compressors is controlled according to the saturation pressure in the carbon dioxide receiver, and each compressor is controlled linearly, so the pressure control in the carbon dioxide receiver is performed with a more precise control system. It becomes possible.

  The invention according to claim 7 prevents cavitation of the carbon dioxide liquid pump for sending the carbon dioxide liquid refrigerant to the load side cooler by controlling the saturation pressure in the carbon dioxide receiver to be constant. A cooling system according to claims 5 and 6 is provided.

  According to this configuration, by controlling the saturation pressure in the carbon dioxide receiver to be constant, the carbon dioxide liquid pump can stably send the carbon dioxide liquid refrigerant to the load side cooler without causing cavitation. Can do.

  The invention according to claim 8 controls the evaporation pressure of carbon dioxide in the cooler to be constant by controlling the saturation pressure in the carbon dioxide receiver to be constant. Provide a cooling system.

  According to this configuration, since the carbon dioxide liquid refrigerant can be stably sent to the cooler by controlling the saturation pressure in the carbon dioxide receiver to be constant, the evaporation pressure of carbon dioxide in the cooler is kept constant. It becomes possible to control to.

  According to a ninth aspect of the present invention, the saturation pressure in the carbon dioxide receiver is variably controlled following the load fluctuation caused by cooling in the cooler. Provide a system.

  According to this configuration, even when a load change occurs due to cooling in the cooler, an appropriate volume of carbon dioxide refrigerant is cooled while variably controlling the saturation pressure in the carbon dioxide receiver according to the load change. Can be sent to the instrument.

  According to the first aspect of the present invention, the saturation pressure in the secondary refrigerant receiver that stores the secondary refrigerant is detected, and the cooling capacity of the primary refrigerant compressor that compresses the primary refrigerant is linearly determined according to the saturation pressure. By controlling, the saturation pressure in the secondary refrigerant receiver is controlled to be constant. As a result, the saturation pressure in the secondary refrigerant receiver is appropriately controlled in accordance with the cooling capacity of the primary refrigerant compressor, so that a sudden drop in the saturation pressure in the secondary refrigerant receiver due to the load fluctuation of the cooler is avoided. be able to.

  According to the second aspect of the present invention, the saturation pressure in the secondary refrigerant receiver can be kept constant only by driving and controlling the primary refrigerant compressor by varying the frequency of the inverter in accordance with the saturation pressure in the secondary refrigerant receiver. Since the control can be performed, in addition to the effect of the first aspect of the invention, it is possible to control the pressure in the secondary refrigerant receiver with a very simple control system.

  According to the invention described in claim 3, since the number of primary refrigerant compressors is controlled according to the saturation pressure in the secondary refrigerant receiver, and each compressor is controlled linearly, the secondary control can be performed with a more precise control system. It becomes possible to control the pressure in the refrigerant receiver.

  According to the invention described in claim 4, since the saturation pressure in the carbon dioxide receiver is appropriately controlled according to the cooling capacity of the ammonia compressor, the saturation pressure in the carbon dioxide receiver due to the load fluctuation of the cooler is abrupt. A decrease can be avoided.

  According to the fifth aspect of the present invention, the saturation pressure in the carbon dioxide receiver is controlled to be constant only by driving and controlling the ammonia compressor by varying the frequency of the inverter in accordance with the saturation pressure in the carbon dioxide receiver. Therefore, in addition to the effect of the invention according to claim 3, it is possible to control the pressure in the carbon dioxide receiver with a very simple control system.

  According to the invention described in claim 6, since the number of ammonia compressors is controlled according to the saturation pressure in the carbon dioxide receiver, and each compressor is controlled linearly, the carbon dioxide receiver has a more precise control system. It becomes possible to perform pressure control.

  According to the invention of claim 7, since the saturation pressure in the carbon dioxide receiver is controlled to be constant, in addition to the effect of the invention of claim 4, the carbon dioxide liquid pump does not cause cavitation, The carbon dioxide liquid refrigerant can be stably delivered to the cooler on the load side.

  According to the invention described in claim 8, since the saturation pressure in the carbon dioxide receiver is controlled to be constant and the carbon dioxide liquid refrigerant is stably delivered to the cooler, the effect of the invention described in claim 4 or 5 is achieved. In addition, the evaporation pressure of the carbon dioxide liquid in the cooler can be controlled to be constant.

  According to the ninth aspect of the invention, since the saturation pressure in the carbon dioxide receiver is controlled to be constant, in addition to the effect of the fourth, fifth, or sixth aspect, the load is reduced by cooling in the cooler. Even when fluctuations occur, an appropriate volume of carbon dioxide refrigerant can be delivered to the cooler while variably controlling the saturation pressure in the carbon dioxide receiver according to the load fluctuation.

Configuration diagram of a cooling system of the present invention constituted by a CO ₂ / NH ₃ natural refrigerant cooling system and a load-side cooling equipment.

Regardless of the amount of heat of the load-side cooling facility or the cooling capacity of the CO ₂ / NH ₃ natural refrigerant cooling system, the present invention suppresses fluctuations in the saturation pressure of the CO ₂ receiver and optimizes the refrigeration capacity of the load-side cooling facility. In order to achieve the objective of realizing a controllable cooling system, the load-side cooler is cooled using a secondary refrigerant applied to the primary refrigerant / secondary refrigerant / cooling system and heat-exchanged by the primary refrigerant. A cooling system that detects a saturation pressure in a secondary refrigerant receiver that stores the liquid refrigerant of the secondary refrigerant and compresses the primary refrigerant according to the saturation pressure. This is realized by controlling the saturation pressure in the secondary refrigerant receiver to be constant by controlling linearly.

Hereinafter, a preferred embodiment according to the cooling system of the present invention will be described with reference to FIG. FIG. 1 is a configuration diagram of a cooling system according to the present invention including a CO ₂ / NH ₃ natural refrigerant cooling system and a load-side cooling facility.

In FIG. 1, the cooling system 1 includes a CO ₂ / NH ₃ unit 2 constituting a CO ₂ / NH ₃ natural refrigerant cooling system, and a load side cooling facility 3 such as a refrigeration apparatus or an air conditioner. CO ₂ / NH ₃ unit 2 together to condense the CO ₂ gas due to evaporation of the CO ₂ receiver 4, NH ₃ solution for storing CO ₂ liquid refrigerant, CO ₂ refrigerant is vaporized in heat exchange with the load-side cooling equipment 3 CO ₂ / NH ₃ cascade condenser 5, CO ₂ liquid NH ₃ compressor 7 the refrigerant to compress the CO ₂ pump 6, the NH ₃ gas to be sent to the load side cooling equipment 3 for condensing, NH condensing the NH ₃ gas ₃ condenser 8, CO ₂ pressure for detecting the saturation pressure of CO ₂ liquid refrigerant condensed NH ₃ NH ₃ receiver 9 for storing gas, NH ₃ NH ₃ expansion valve 10 for decompressing the gas, CO ₂ receiver 4 sensor 11, CO ₂ pressure CO ₂ pressure regulator 12 for controlling the saturation pressure of CO ₂ liquid refrigerant in the CO ₂ receiver 4 on the basis of the pressure detection information from the sensor 11, and the frequency is changed by NH ₃ compressor 7 Capacity of cooling capacity It is constituted by an inverter 13 for controlling the near (proportionally). The load-side cooling facility 3 includes a cooler 14 and a CO ₂ flow rate adjustment valve 15 that controls the flow rate of the CO ₂ refrigerant liquid supplied to the cooler 14.

  The CO 2 refrigerant side of the CO 2 / NH 3 natural refrigerant cooling system in the cooling system 1 is composed of various devices such as a CO 2 receiver 4, a CO 2 / NH 3 cascade capacitor 5, a CO 2 liquid pump 6, a cooler 14, and a CO 2 flow rate adjusting valve 15. A CO2 refrigerant circuit (secondary refrigerant circuit) is connected by a piping system as shown in FIG.

Further, the NH ₃ refrigerant side of the CO ₂ / NH ₃ natural refrigerant cooling system in the cooling system 1 is an NH 3 compressor 7, an NH ₃ condenser 8, an NH 3 receiver 9, an NH ₃ expansion valve 10, and a CO ₂ / NH ₃ cascade. An NH ₃ refrigerant circuit (primary refrigerant circuit) is connected by a piping system as shown in FIG.

Then, the NH ₃ gas compressed by the NH ₃ compressor 7 is condensed by the NH ₃ condenser 8 and stored in the NH ₃ receiver 9, and then depressurized by the NH ₃ expansion valve 10 to be CO ₂ / NH ₃ cascade. It is supplied to the capacitor 5.

On the other hand, CO _{2 gas,} CO 2 / NH ₃ is condensed by evaporation of the NH ₃ solution in the cascade condenser 5 becomes CO ₂ refrigerant liquid, CO ₂ pump after the CO ₂ refrigerant liquid stored in the CO ₂ receiver 4 3 is supplied to the cooler 14 of the load side cooling facility 3.

Here, the saturation pressure of the CO ₂ liquid refrigerant in the CO ₂ receiver 4 is controlled as follows. That is, the saturation pressure of CO ₂ liquid refrigerant in the CO ₂ receiver 4 is detected at all times by the CO ₂ pressure sensor 11 that is attached to the CO ₂ receiver 4. Further, the pressure detection information of the CO ₂ pressure sensor 11 is transmitted to the CO ₂ pressure regulator 12.

Thus, CO ₂ pressure regulator 12 based on the pressure detection information from the CO ₂ pressure sensor 11, the saturation pressure of CO ₂ liquid refrigerant in the CO ₂ receiver 4 are set in advance by the CO ₂ pressure regulator 12 The capacity of the cooling capacity of the NH ₃ compressor 7 is controlled linearly (proportional) by changing the frequency of the inverter 13 so as to maintain the pressure. In other words, the CO ₂ pressure regulator 12 variably controls the frequency of the inverter 13 based on the pressure detection information from the CO ₂ pressure sensor 11, and the CO ₂ receiver according to the capacity of the cooling capacity of the NH ₃ compressor 7. The saturation pressure of the CO ₂ liquid refrigerant in 4 is changed appropriately.

In this way, by controlling the saturation pressure of CO ₂ liquid refrigerant in the CO ₂ receiver 4 constant boiling of a saturated solution of CO ₂ liquid refrigerant in the CO ₂ receiver 4 is suppressed. Therefore, by boiling saturated solution of CO ₂ liquid refrigerant in CO ₂ receiver 4 is suppressed, it is possible to prevent cavitation at the suction side of the CO2 pump 6. As a result, CO2 pump 6 is capable of providing a stable CO ₂ liquid refrigerant to the cooler 14 of the load-side cooling equipment 3.

By holding the saturation pressure of CO ₂ liquid refrigerant in the manner in CO ₂ receiver 4 constant, the saturation pressure of CO ₂ liquid refrigerant supplied to the cooler 14 of the load-side cooling equipment 3 is constant, CO ₂ Evaporation pressure is also constant. Such control is performed by feedback control by the CO ₂ pressure sensor 11, the CO ₂ pressure regulator 12, and the inverter 13, and therefore, regardless of the change in the heat quantity of the cooler 14 in the load side cooling facility 3, the CO 2 It becomes possible to maintain the operating conditions of the entire system of the ₂ / NH ₃ natural refrigerant cooling system constant.

To summarize the contents described above, the cooling system 1 of the present invention detects the saturation pressure of CO ₂ liquid refrigerant in the CO ₂ receiver 4 by CO ₂ pressure sensor 11, the saturation pressure of CO ₂ liquid refrigerant is constant Thus, the NH ₃ compressor 7 of the NH ₃ refrigerant circuit is controlled linearly by the inverter 13. Thus, with respect to the change amount of heat in the load-side cooling equipment 3, the saturation pressure of CO ₂ liquid refrigerant in the CO ₂ receiver 4 can the control constant, and, CO ₂ liquid refrigerant from the CO ₂ pump 6 Can be delivered stably. In other words, a saturation pressure control system that enables stable liquid feeding of the CO ₂ liquid pump 6 by controlling the saturation pressure in the CO ₂ receiver 4 to be constant with respect to changes in the amount of heat of the load side cooling facility 3. Can be realized.

Moreover, since the boiling in the saturated liquid in the CO ₂ receiver 4 can be suppressed by controlling the saturation pressure in the CO ₂ receiver 4 in this manner, cavitation of the CO ₂ liquid pump 6 is prevented. Thus, the CO ₂ saturated liquid can be stably supplied to the load side.

Due to the operation as described above, the cooling system of the present invention can reduce the saturation pressure in the CO ₂ receiver 4 even when the cooling capacity is large or the load fluctuation is large with respect to the heat amount of the load side cooling facility 3. It is possible to prevent the cooling failure by controlling to be constant. In addition, it is possible to prevent the cooling failure by allowing the CO ₂ liquid pump to send liquid stably. Further, in the CO ₂ / NH ₃ natural refrigerant cooling system applied to the cooling system of the present invention, even if a CO ₂ liquid refrigerant having a large pressure change is used, fluctuations in saturation pressure in the CO ₂ receiver 4 are suppressed. Thus, the CO ₂ liquid refrigerant can be stably supplied to the load-side cooling facility 3.

That is, in the cooling system of the present invention, the cooling of the load-side cooling facility 3 is controlled by linearly controlling the capacity of the refrigeration capacity of the NH ₃ compressor 7 so as to keep the saturation pressure of the CO ₂ liquid refrigerant constant. Even if the heat quantity of the cooler 14 fluctuates, it is possible to supply a stable saturated liquid of CO ₂ liquid refrigerant to the cooler 14. As a result, the operating conditions of the entire cooling system 1 constituted by the CO ₂ / NH ₃ unit 2 constituting the CO ₂ / NH ₃ natural refrigerant cooling system and the load side cooling equipment 3 including the cooler 4 are made constant. be able to.

In other words, in the CO ₂ / NH ₃ natural refrigerant cooling system applied to the load side cooling facility 3 such as a refrigeration apparatus or an air conditioner, the CO ₂ liquid refrigerant cooled and condensed in the NH ₃ refrigeration cycle is converted into a CO ₂ liquid. It is supplied to the load side cooling facility 3 by the pump 6. In this case, in the prior art, by the saturation pressure of CO ₂ liquid refrigerant CO ₂ receiver 4 when a reduced load, such as a refrigeration apparatus or air-conditioning device is rapidly reduced, CO ₂ in the CO ₂ receiver 4 Boiling occurs in the liquid refrigerant, and the liquid feeding force of the CO ₂ liquid refrigerant delivered from the CO ₂ liquid pump 6 becomes unstable. However, in the cooling system of the present invention, the CO ₂ / NH ₃ natural coolant circulation system, by the saturation pressure of CO ₂ liquid refrigerant in the CO ₂ receiver 4 controls the cooling capacity to be constant, the load-side cooling Even when the load on the facility 3 is reduced, the liquid can be stably fed from the CO ₂ liquid pump 6 to the load-side cooling facility 3.

  As mentioned above, although the specific Example of the cooling system based on this invention was described, this invention is not limited to the said Example, A various change can be made unless it deviates from the mind of this invention, The present invention naturally extends to the modified one.

The cooling system of the present invention can be effectively used in fields such as a refrigeration apparatus and an air conditioner that employ a cooling system using a primary refrigerant / secondary refrigerant / cooling system or a CO ₂ / NH ₃ natural refrigerant cooling system.

1 Cooling System 2 CO ₂ / NH ₃ Unit 3 Load-side Cooling Equipment 4 CO ₂ Receiver 5 CO ₂ / NH ₃ Cascade Capacitor 6 CO ₂ Liquid Pump 7 NH ₃ Compressor 8 NH ₃ Condenser 9 NH ₃ Receiver 10 NH ₃ Expansion Valve 11 CO ₂ pressure sensor 12 CO ₂ pressure regulator 13 Inverter 14 Cooler 15 CO ₂ flow rate regulating valve

Claims (9)

A cooling system that is applied to a primary refrigerant / secondary refrigerant / cooling system and cools a load-side cooler using a secondary refrigerant heat-exchanged by the primary refrigerant,
By detecting the saturation pressure in the secondary refrigerant receiver that stores the liquid refrigerant of the secondary refrigerant, and linearly controlling the cooling capacity of the primary refrigerant compressor that compresses the primary refrigerant according to the saturation pressure, The cooling system characterized by controlling the saturation pressure in the said secondary refrigerant receiver uniformly.   The saturation pressure in the secondary refrigerant receiver is controlled to a constant pressure by driving and controlling the primary refrigerant compressor by an inverter that detects the saturation pressure in the secondary refrigerant receiver and performs frequency control. The cooling system according to claim 1, wherein:   The saturation pressure in the secondary refrigerant receiver is controlled to a constant pressure by detecting the saturation pressure in the secondary refrigerant receiver and controlling the number of two or more primary refrigerant compressors. The cooling system according to claim 1 or 2. In the cooling system that employs the ammonia used in the carbon dioxide / ammonia natural refrigerant cooling system as a primary refrigerant and the carbon dioxide as a secondary refrigerant,
By detecting a saturation pressure in a carbon dioxide receiver that stores the liquid refrigerant of carbon dioxide, and linearly controlling a cooling capacity of an ammonia compressor that compresses the ammonia based on the detected saturation pressure, the dioxide dioxide is controlled. A cooling system characterized by controlling a saturation pressure in a carbon receiver to be constant.   The saturation pressure in the carbon dioxide receiver is controlled to a constant pressure by driving and controlling the ammonia compressor by an inverter that detects the saturation pressure in the carbon dioxide receiver and performs frequency control. The cooling system according to claim 4.   5. The saturation pressure in the carbon dioxide receiver is controlled to a constant pressure by detecting the saturation pressure in the carbon dioxide receiver and controlling the number of two or more ammonia compressors. 5. The cooling system according to 5.   The cavitation of the carbon dioxide liquid pump for sending the carbon dioxide liquid refrigerant to the load side cooler is prevented by controlling the saturation pressure in the carbon dioxide receiver to be constant. The cooling system described.   The cooling system according to claim 5 or 6, wherein the evaporation pressure of carbon dioxide in the cooler is controlled to be constant by controlling the saturation pressure in the carbon dioxide receiver to be constant. 7. The cooling system according to claim 4, wherein the saturation pressure in the carbon dioxide receiver is variably controlled following a load fluctuation caused by cooling in the cooler.

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